The present invention relates to soldering and soldering machines, and more specifically to a hot air circulation apparatus and method for wave soldering machines.
Wave soldering machines are typically used to solder components onto printed circuit boards. Such machines employ a fluxer for applying flux to the solderable surfaces of the printed circuit boards, preheaters to preheat the printed circuit boards, and a solder wave to apply liquid solder to the solderable surfaces. One such machine is manufactured by Electrovert, Inc.
The preferred flux used in wave soldering machines is a resin flux. Resin fluxes provide smooth finished surfaces. However, resin fluxes contain environmentally harmful and flammable volatile organic compounds.
An alternative to resin fluxes is a water-based flux, such as the 970 and 970CTX flux products from Kester Corporation. An air knife is typically located after the flux tank to remove excess flux from printed circuit boards and prevent dripping on preheater surfaces. A warm gentle airflow is required so as not to blow the flux off the board.
The water-based flux is environmentally safe, but when used in wave soldering machines suffers from the disadvantage that the water cools the printed circuit board and causes solder balls to form. Previous attempts at making the water-based flux usable in wave soldering machines have been unsuccessful.
Therefore, it would be desirable to provide an apparatus and method that would allow wave soldering machines to use the water-based fluxes.